Project Abstract Continued studies on basic mechanisms of atrophic age related macular degeneration (AMD) are proposed with translation of this work to establish novel therapies. Early AMD progresses to late blinding forms of the disease by following one of two divergent pathways; atrophic AMD or geographic atrophy (GA) is associated with progressive senescence and death of the retinal pigment epithelium (RPE), while choroidal neovascularization (CNV) is associated with growth of new vessels under the retina. In the last grant period we developed strong support for our hypothesis that increased expression of bone morphogenetic protein-4 (BMP4) in RPE induces features characteristic of atrophic AMD, and inhibits CNV; thus mediating a molecular switch that determines which late form of AMD a patient develops. One of the major responses to increased BMP4 expression in RPE is upregulated protein expression of the chaperone aB crystallin. We hypothesize that in early AMD, increased BMP4 expression leads to RPE senescence and a novel reactive neuroprotective response with increased expression of aB crystallin from RPE; however as disease progresses, this response is overwhelmed and further sustained oxidative stress results in progression to GA. We then hypothesize that aB crystallin-derived oligopeptides with chaperone activity can provide similar protection of RPE from oxidative stress and other injuries and can be selectively transported into the RPE. Furthermore, novel aB crystallin peptide nanoparticles can be assembled and optimized to effectively rescue dysfunctional RPE in culture, and in multiple murine models with features of GA. This work is highly significant since there is currently no effective therapy for GA. The hypotheses will be tested using the following Specific Aims: Aim #1. Determine the molecular, cellular, and functional inter-relationships between BMP4 and aB crystallin in RPE and the effect of oxidative stress on these processes. Aim # 2. Develop and optimize aB crystallin peptide nanoparticles that inhibit effects of various forms of stress in RPE cells grown in culture. Aim # 3. Determine the pharmacokinetics of aB crystallin peptide nanoparticles after intraocular or systemic delivery and determine the ability of these nanoparticles to inhibit progression of disease in multiple murine models with features of GA .